Article by Dr. Frank, Cannabis Culture
Last week, I wrote an article on Smart Approaches to Marijuana’s approach to cannabis legalization. One of the things that really stood out for me was the the motto “Preventing another big tobacco’. So, I thought to do a bit of a side-by-side comparison, and see if cannabis really is another big tobacco …
As I’ve written in ‘Busting the Overdose Myth’, cannabis is pretty much one of the least lethal plants on this planet. Even raw potatoes are more toxic! Nicotine, on the other hand, is possibly as toxic as cyanide (with some caveats). The median lethal dose of nicotine is 0.5 to 1.0 mg/kg, or 40 to 60 mg in an average human being. There is essentially no comparison between the two in terms of toxicity. There are also a huge number of other chemicals in tobacco that are poisonous, such as arsenic, benzene, cadmium, methanol, toluene and many more.
Cannabis smoke vs. tobacco smoke
There’s a lot of literature out there saying things like ‘one joint is equal to 5/10/20/insert whatever number of cigarettes per day’. This is pretty much a myth. Yes, burning plant matter and inhaling smoke can lead to health problems (e.g. bronchial epithelial ciliary loss, bronchitis), but it seems that there is a lot of conflicting evidence on how carcinogenic cannabis is. Why is this? One simple answer is nicotine. Not only is it addictive, but to quote Robert Melamede’s ‘Cannabis and tobacco smoke are not equally carcinogenic’:
“ … [D]espite potentially higher levels of polycyclic aromatic hydrocarbons found in cannabis smoke compared to tobacco smoke (dependent on what part of the plant is smoked), the THC present in cannabis smoke should exert a protective effect against pro-carcinogens that require activation. In contrast, nicotine activates some CYP1A1 [cytochrome P1A1]activities, thus potentially increasing the carcinogenic effects of tobacco smoke.”
Essentially, this means that the cannabinoids in cannabis smoke may protect against carcinogens, perhaps by inhibiting some of the activity of the liver enzyme CYP1A1. Tobacco, meanwhile, activates some activities in this liver enzyme and increases the carcinogenic effect of the smoke.
Now, there are some studies that suggest that inhaling cannabis smoke may increase the chances of developing lung cancer. Whether such studies control for tobacco smoking as well (remember: many people mix the two, especially outside of North America) as well as other factors (e.g. diet, exercise) depends upon how well the study was carried out and its methodology. Some studies are good, some are not. There is one particularly interesting study that rarely gets mentioned, and that is Donald P. Tashkin’s ‘Effects of Marijuana Smoking on the Lung’, where he states:
“Several case reports have implicated marijuana smoking as an etiologic factor in pneumothorax/pneumomediastinum and bullous lung disease, although evidence of a possible causal link from epidemiologic studies is lacking. In summary, the accumulated weight of evidence implies far lower risks for pulmonary complications of even regular heavy use of marijuana compared with the grave pulmonary consequences of tobacco.”